1. Field of the Invention
The present invention relates to an inter-system serialization control system for controlling a plurality of systems serially and exclusively for accessing shared resources.
A system in which a plurality of computers are connected via a communication channel is called a complex system. Each computer system in the complex system is hereinafter referred to as a cluster. Along with the development of computer systems to be used in various fields and the increasingly large scale of such systems for use, for example, as a computer system for a bank, complex systems have been recently used. In such a complex system, an operation of accessing shared resources in, for example, network data bases, relational data bases, general data sets, and so forth, commonly used among the clusters, must be controlled so that the clusters access the shared resources serially or exclusively. It has been desired to decrease the overhead in this serialization control.
2. Description of the Related Arts
As a conventional inter-cluster serialization control system for accessing shared resources, there are two known systems: one is a reserve-release system and the other is an inter-cluster communication system.
In the conventional reserve-release system, there is a problem in that reserving and releasing of resources are required each time an access request is made so that the serialization control has a large amount of overhead. In addition, since the logical processing unit used for serialization control in the conventional reserve-release system is a volume, with a volume being comprised of a plurality of magnetic disks for example, and the size of the volume is as large as, for example, several Gbytes, the unit used for serialization control is quite large so that there is a tendency for a queue to be easily generated among the clusters.
In a conventional inter-cluster communication system, there is a problem in that the communication overhead increases in proportion to an increase in the number of clusters in the complex system. The communication overhead is the time necessary for communication and the processing time required by a CPU in each cluster. In addition, the performance in processing a transaction cannot be greater than the performance of the communication channel.